Conventionally, for example as described in Patent Literature 1, startup controls for a synchronous motor drive device of an electric compressor have considered both startup performance with respect to a differential pressure between low pressure refrigerant and high pressure refrigerant, as well as the life span of an inverter circuit.
In Patent Literature 1, a target current value for a startup current that flows from an inverter circuit to a stator coil for a following startup is determined based on a current value that flows from the inverter circuit to the stator coil when a stop command for a compressor is generated.
If the current value is large when the stop command for the compressor is generated, a pressure difference is considered to be large, and the target current value is set to be large. If the current value is small when the stop command for the compressor is generated, the pressure difference is considered to be small, and the target current value is set to be small.